Multiplexer Test Cables for Multi-Lane Measurement Accuracy
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Solution Overview
Problem
Existing test and measurement instruments face challenges in efficiently testing multiple signal lanes of DUTs due to limited input channels, manual connection errors, and difficulties in de-embedding switch impacts, especially at higher frequencies.
Innovation Solution
A multiplexer-enabled cable or test fixture with integrated multiplexer, memory, and processor that automatically switches between signal lanes, storing calibration parameters to de-embed cable effects and connect DUTs to test instruments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If manual cable movement is used to test each signal lane, then testing can be performed with limited input channels, but the process becomes error-prone and time-consuming
Solution Approach 1:
The system performs self-testing through automated multiplexer switching and calibration parameter storage. The test fixture automatically cycles through signal lanes using the multiplexer, eliminates manual connection errors, and maintains calibration data for consistent measurements across all lanes without requiring human intervention for each connection change.
Solution Approach 2:
The multiplexer dynamically switches connections between signal lanes and test instrument inputs, enabling automated testing of multiple lanes with a limited number of instrument channels. This dynamic switching replaces static manual connections, improving both productivity and reliability.
2Extent of automation
If RF switches are used to automate testing of all signal lanes, then automation is achieved, but de-embedding switch impacts becomes difficult at higher frequencies
Solution Approach 1:
The patent extracts the switching function from external RF switches and integrates it directly into the test fixture's multiplexer circuitry. This eliminates the need for separate de-embedding of switch impacts, as the switching occurs at the fixture level where calibration parameters can be directly applied to compensate for any introduced effects.
Solution Approach 2:
Calibration parameters are pre-measured and stored for each signal lane before actual testing begins. This preliminary calibration captures the electrical characteristics of each lane including any multiplexer effects, allowing for accurate compensation during subsequent measurements without requiring complex real-time de-embedding calculations.
3Measurement precision
If calibration parameters are stored and used to de-embed cable effects, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple functions into the test fixture: the multiplexer for lane switching, the calibration parameter storage memory, and the processor for managing measurements all integrate into a single unified device. This merging reduces overall system complexity compared to using separate external instruments for each function while maintaining high measurement accuracy through stored calibration data.
Data Source
AI summary
A calibrated test and measurement cable for connecting one or more devices under test and a test and measurement instrument, including a first port structured to electrically connect to a first signal lane, a second port structured to electrically connect to a second signal lane, a third port structured to electrically connect to a test and measurement instrument, and a multiplexer configured to switch between electrically connecting the first port to the third port and connected the second port to the third port. The first and second signal lanes can be included on the same device under test or different devices under test. An input can receive instructions to operate the multiplexer.